Partnership Helps Carriers Evolve VoIP Offering to Leverage IMS-based Capabilities

SAN JOSE, CA, and CHELMSFORD, MA, March 15, 2006 – At Spring VON 2006 (Booth #517), Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, and Atreus Systems™, the premier supplier of provisioning software for IMS, VoIP and advanced IP service bundles, today announced a partnership that will enable service providers to reduce operating costs and speed the delivery of hosted VoIP services. As a member of Sonus' Open Service Partner Alliance (OSPA), Atreus will partner with Sonus to deliver a solution that empowers carriers to generate new revenue streams by simplifying the delivery of a suite of value-added consumer and business voice services, including Hosted PBX, business trunking (Integrated Access), conferencing, and voice VPN services.

The joint solution has been selected by one of the largest carriers in North America as the foundation for its next generation voice network. By deploying Atreus' automated provisioning and customer self-management software over Sonus' industry-leading IP Multimedia Subsystem (IMS)-ready architecture, service providers can take advantage of a complete solution that ensures flexibility, reliability and the rapid delivery of bundled VoIP offerings. The joint solution automates the processes to quickly turn up hosted voice, messaging, conferencing and voice VPN capabilities for residential and enterprise customers. The key features will:

• Streamline service ordering and provisioning using simplified, self-management portals;
• Simplify complex operational issues including PSTN interconnect, Local Number Portability, Updating Directory Listings and E-911;
• Create differentiated voice service bundles by market segment; and
• Simplify CPE provisioning, enterprise site creation and management

“This partnership enables Sonus Global Services to extend its capabilities with a fully integrated service delivery platform. The solution assists carriers across the globe to increase revenue and contribution per customer by leveraging their existing investments to support VoIP and incorporate high-value business applications,” said Steve Edwards, chief marketing officer, Sonus Networks. “Together, we're committed to offering our customers flexible, carrier-grade VoIP solutions today, while supporting providers' future requirements for converged voice-video-data services.”

“Sonus' leadership in next-generation packet voice technologies, coupled with Atreus' proven expertise in automated service provisioning, enables our carrier customers to enhance their business through the rapid deployment of feature-rich consumer and business VoIP bundles,” said Len Castelli, vice president of business development, Atreus Systems. “This partnership will help service providers differentiate their products and win business with competitive new voice offerings.”

About Atreus Systems

Atreus Systems™ is the premier supplier of provisioning software for IMS, VoIP and advanced IP service bundles. Atreus leads the market with award winning products and is the vendor of choice for the delivery of advanced IP services by leading providers, including Telus, Aliant, Voila IP and Xspedius. Atreus has formed strategic partnerships with BroadSoft, Ericsson, Level 3, and SONUS, delivering carrier-class reliability and scalability for IMS, VoIP, and advanced IP bundles. For more information, visit www.atreus-systems.com.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of Voice over IP (VoIP) infrastructure solutions for wireline and wireless service providers. With its comprehensive IP Multimedia Subsystem (IMS) solution, Sonus addresses the full range of carrier applications, including residential and business voice services, wireless voice and multimedia, trunking and tandem switching, carrier interconnection and enhanced services. Sonus' voice infrastructure solutions are deployed in service provider networks worldwide. Founded in 1997, Sonus is headquartered in Chelmsford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

This release may contain forward-looking statements regarding future events that involve risks and uncertainties. Readers are cautioned that these forward-looking statements are only predictions and may differ materially from actual future events or results. Readers are referred to the “Risk Factors” section of Sonus' Annual Report on Form 10-K, dated March 14, 2006, filed with the SEC, which identify important risk factors that could cause actual results to differ from those contained in the forward-looking statements. Risk factors include among others: the impact of material weaknesses in our disclosure controls and procedures and our internal control over financial reporting on our ability to report our financial results timely and accurately; the unpredictability of our quarterly financial results; risks associated with our international expansion and growth; consolidation in the telecommunications industry; and potential costs resulting from pending securities litigation against the company. Any forward-looking statements represent Sonus' views only as of today and should not be relied upon as representing Sonus' views as of any subsequent date. While Sonus may elect to update forward-looking statements at some point, Sonus specifically disclaims any obligation to do so.

Sonus is a registered trademark of Sonus Networks, Inc. Sonus GSX9000 Open Services Switch, PSX Call Routing Server, SGX Signaling Gateway, and the Sonus Insight Management System are trademarks of Sonus Networks, Inc. All other company and product names may be trademarks of the respective companies with which they are associated.